The Sun and the Seasons

The seasons are governed by the tilt of the Earth’s axis in space as it journeys around the Sun in a year. When the South Pole of the Earth is tilted towards the Sun, this is our Summer. Six months later, when the South Pole is tilted away from the Sun, it's our Winter. In between these we have Autumn and Spring.

The Sun and the seasonsArtist: Frey Micklethwait. Source: Museum Victoria.

Temperatures on our planet are not determined by the distance of the Earth from the Sun. Rather it is the angle of the Sun’s rays striking the Earth. In Summer, the Sun is high in the Sky and the rays hit the Earth at a steep angle. In winter, the Sun is low in the Sky and the rays strike the Earth at a shallow angle.

The seasons don’t begin on one day and finish on another. That's because our orbit around the Sun is continuous. It actually takes quite some time for the Earth to heat up or cool down, and that’s why the seasons change gradually.

So when do we actually start the seasons?

In some parts of the world, such as Australia, seasons begin on the first day of a particular calendar month - in March for Autumn, June for Winter, September for Spring and December for Summer. In other countries such as Britain, it’s accepted that the seasons begin on the dates that the Earth passes four special points in its orbit about the Sun.

Spring Equinox (AEST)

On the day of the Spring Equinox, the Earth’s poles are the same distance from the Sun. In Melbourne, the Sun rises due east, sets due west and gets to 52° above the horizon at noon. On this day there are roughly 12 hrs of day and 12 hrs of night.

Summer Solstice (AEDT)

2014 December 22, 10:032015 December 22, 15:482016 December 21, 21:44

The Sun in summerArtist: Frey Micklethwait. Source: Museum Victoria.

On the day of Summer Solstice, the Earth’s south pole is tilted towards the Sun. The Sun rises south of east, sets south of west and reaches 75 1/2° above the horizon at noon. This is, usually, the longest day of the year.

Autumn Equinox (AEDT)

2014 March 21, 03:572015 March 21, 09:452016 March 20, 15:30

The Sun in autumnArtist: Frey Micklethwait. Source: Museum Victoria

On the day of the Autumn Equinox, the Earth’s poles are the same distance from the Sun. The Sun rises due east, sets due west and reaches 52° above the horizon at noon. There are roughly 12 hrs of day and 12 hrs of night.

Winter Solstice (AEST)

2014 June 21, 20:512015 June 22, 02:382016 June 21, 08:34

The Sun in winterArtist: Frey Micklethwait. Source: Museum Victoria.

On the day of Winter Solstice, Earth’s south pole is tilted away from the Sun. The Sun rises north of east, sets north of west and reaches 28 1/2° above the horizon at noon. This is, usually, the shortest day of the year.

Comments (144)

Exccelent I needed this info for my garden , right going out to my garden right now to plant garlic as your site has made it clear that the Autumn Equinox was on the 20th of march!! so better get those garlics in the ground immidiately, thankyouoooo!, mara

This site is brilliant, easy to understand, informative. In all of my years learning about our planet, no teacher could EVER explain the Equinox and the Solstice so clearly. Good on everyone who has worked hard to make it such a success. This site is now 'offically' bookmarked! Fantastic work.

Hi I have a friend in USA who is a pagan priestess and is coming to australia in December for solstice conference do you have a contact or know of an expert in the solstice field in Australia? thanks for your help

The Discovery Centre can answer questions that relate to Museum Victoria's Collection and Research areas, including Science. If you have specific questions relating to astronomy and meteorology, such as the solstice, you can ask one of our experts on staff by contacting the Discovery Centre directly.

stephen Robards
20 December, 2009 13:05

What is the time difference between Melbourne and Wollongong for the Summer Solstice. You note that it is 4.47am is this same time for both locations?

Hi, I like to know if there's anyway I can take a compass reading of a building's facing direction using the reference of the sun (to detect a true south direction)?
I have problem taking accurate compass reading due to interference of magnetic field from man-made magnetic field (like underground wiring and light pole etc). Hope you can help. Thanks.

Compasses indicate magnetic north or south as they react to the Earth’s magnetic field but that’s offset with respect to our planet’s rotational axis (what most call geographic or true north/south). The direction of magnetic north or south is therefore slightly different. It's possible to find south using the position of the Sun in the sky but it's hard to be really accurate. A reasonable result can be got by observing the motion of the Sun across the sky. Wait for local noon by using a clock on standard time (simpler than having to allow an hour for daylight savings). At that time the Sun will be at its highest point above the horizon, so face the Sun and south will be behind you if you are in the Southern Hemisphere (or north will be behind you if in the Northern Hemisphere). Better still, use a sundial or a tall pole that will throw a shadow towards south at local noon (or towards north if in the Northern Hemisphere). You can then compare compass readings at the building and some well away from it with your noon observing of the Sun. Overall you should get a pretty good facing direction. These websites will give more information:

This is rather a stupid and uninformed question but I will ask it anyway - "In plain language without the scientific stuff please, what is the difference between the terms "solstice" and"equinox" - obviously, they don't mean the same thing so what essentially is the main difference.

Hi John - The equinoxes occur when the Sun is right across the celestial equator, and so day and night are of the same length for all observers on Earth. The equinoxes happen in March and September. In June and December are the solstices, when the Sun reaches its northernmost (in June), or southernmost (in December) point in the sky, and appears to stop (in its north-south movement) before reversing and heading back in the other direction.

Rob
22 June, 2010 09:22

Excellent description.
Why do the times/dates for soltices and equinoxes vary a bit from year to year?

Thank you very much for nice concise information. I came to find the date of the winter solstices but was enlightened by the explanation of the difference between that and the equinox. I probably should have already know that but now I do and it’s thanks to this site

The date and time of the equinoxes and solstices change slightly because the Earth's orbit around the Sun is not precisely 1 year. The equinoxes and solstices happen when the Earth reaches a precise point in its orbit around the Sun.

However the beginning of the year does not happen at the exact same point every year. We count years as being either 365 or 366 days long, but the orbit actually takes about 365.242 days to go from one March equinox to the next.

Thus in a non-leap year, the equinox will be about 0.242 days (approximately 5 hours 50 minutes) later than the previous equinox, while in a leap-year it will be 0.758 days (18 hours 10 minutes) earlier. Note that these figures aren't exact, and the combined effects of gravity from the Moon, the Sun and the other planets also cause a few minutes variation from year to year.

That's correct - if the Earth's axis was not tilted, we would not experience the seasons as we understand them, since the Sun's rays would not be striking the surface of the Earth at such steep angles. If the Earth was not tilted, the Sun's rays would strike the Earth at a uniform angle.

Nice to be right for a change!!
25 June, 2010 22:13

Thank you for saving my marriage and answering when the shortest day of the year is. I knew l was right he knew he was.... and as it happens l was.

Yesterday I was reading my original 1829 bound edition of 'The Mirror.' On page 368 was the following assurance: “The tip of the cat’s nose is always cold, except on the day of the (northern) sumer solstice, when it becomes lukewarm.” I’ve put an automated reminder on my computer to check our two moggies’ proboscises at mid-morning next 22 December.

Thanks for the info.
I say boo to June 21, we've hardly had a cold day here yet, I've only got to wear my new boots once!! Great site thanks for all the useful information.
I will check my cats nose on December 22 as well, although living in mid Qld its likley to be hot anyway near Christmas.

Can you tell me what people who live north of the tropic of capricorn but south of the equator experience. I have been told they experience 2 equinoxes and 2 solstices each time not one. Is this correct or fallacious?

Hi Felicity - It is not true that there are two summer solstices at these locations. The summer solstice happens at a specific point in the Earth’s orbit. What is true is that the Sun will appear directly overhead twice a year in these locations. However this is not on the day of the summer solstice. On this day the day length is longest, and the Sun appears the most southerly, and this will only happen once each year no matter where you are.

Linda
21 August, 2010 13:43

Great information thanks. I have one question though, I was told that the equinox also relates to wind, and that typically Victoria is at it's windiest in August & September. can you please advise if this is true, and, if so, why.

Thanks for a brilliant site. Just wanted to echo the previous question; I'd always heard that the equinox effects the wind and that March and September can be much more blowy. Is that true or coincidence? Is there any connection with spring tides too? Thanks

We do not believe there is any relation between the equinox, and the weather or tides. However it possibly is more windy between the seasons because that is the pattern in that part of the world at that time, thus, a coincidence.As far as the effect on the spring tides, it should be pointed out that the “Spring” does not refer to the season in this instance, it refers to an earlier meaning, to spring forward or to rise. This is when the Sun and Moon align to give a higher than normal tide. The opposite of spring tide is neap tide when it is lower than usual.

Liz
2 October, 2010 22:32

Thanks, I'm so glad I asked!

Ronnie
14 September, 2010 20:52

Very interesting and informative website. However, I would be interested to know when Australia altered the change of seasons to the 1st of the month, ie 1st March, 1st June, 1st September and 1st December. As Australian students, in the '50s and '60s, we were always taught that the seasons commenced on the 21st of the aforementioned months in line with Britain.

Hi Ronnie, there is not actually an 'official start date' for seasons. When a season starts on a certain day it is only by convention. There is no government act or universally accepted scientific definition for what constitutes a season.

Most countries popularly use the equinox and solstice dates to 'start' the seasons' but meteorologists around the world start counting the seasons in the same way that Australians do - on March 1st, June 1st etc

Hi JB, the Summer and Winter Solstices are a moment in time when the Sun is at its most northern or highest in the sky and most southern or lowest in the sky extremes. This year this will occur on the 21 June at 11:28 UTC time and at 21st December at 23:38 UTC time. So in answer to your question about how long a solstice is, it is just a point in time. Have a look at our infosheet on the path of the sun for more information.

Elizabeth Visnon
16 November, 2010 01:28

great information thanks. now i know more about the sun and the seasons!

I don't see why we are told here in Australia, that our four seasons start on the first day of the month,i.e. Dec, March, June, Sept. Why is it different to the Northern Hemishphere where the seasons start on the 21st day of these months?

Thanks for the details because this is important to me as I mark the true Saxon Year-teller (calendar) from its erstwhile beginnings, namely, the year begins with the Evennights (Equinox). This year-teller is the perfect one, never needing a leap year and self rights every year at evennights. It dates from the time the law was given to Moses and handed down into Saxon culture because the Saxons get their name from the Persians who called them, the Saka-suni, meaning, Isaac-sons. The Greeks and Romans applied their own versions of this name from whence we get Saxons. The reason the name was given to us was because we we living in bannishment in northern Assyria around 700 BC, becoming lost to history, and were sometimes called the lost tribes of Isaac (Abraham, Isaac, Jacob). Our year-teller has months of 30 days and months were named after agricultural events, such as Winemonth, Havestmonth, Summermonth, Barleymonth and so on. Our weeks of 7 days were called, Onesday, Twosday, Threesday, and so on. Our feest days were the correctional days to fill in the caps to make up the full year.

When watching the moon recently, I have noticed the half moon rising has its bright side facing a southerly direction. I would have expected the light to be coming from the north, seeing its our exquinox. can you settle my mind on this please. I have been thinking its because Earth has had an axis change since the earthquake in Japan. looking forward to hearing from you.

Hi Diana, the bright side of the Moon always faces the Sun of course as that is why it is bright. From Melbourne this would generally mean that the bright side is facing north. The axis of the earth has not appreciably changed because of the recent earthquakes, but may have shortened our day by about a millionth of a second. It certainly would not have changed the sun angle onto the moon.

Phill
7 April, 2011 20:57

succinct explanation - cuts through the crap that can sometimes accompany astronomical discussion, but then astronomy is never simple is it?

Thanks for such a succint explanation for what can be a confusing topic. We always like to know when the shortest day is as, knowing that each day from then will be slightly longer, lifts our spirits. This is especially relevant for people who suffer from Seasonal Affective Disorder (SAD).

Thank you Museum Victoria. I am giving a talk about the winter solstice tomorrow night and it was difficult to find books to answer my questions. Now I know exactly when the farthest axial tilt occurs. I didn't realise it was different every year. I was interested to read about the similarities of the celebration in so many cultures.

i have increasingly become more interested in the correlation of the planetary alignments and seasonal changes and this site has so much easy to understand explainations. i am so greatful for your input and comments. A City Farm not far from where i live celebrates the winter solstice every year with the community and interested ones who come along to join with us... so thank you for the accurate info..
Alan

Great web page. I've been counting down to 3.16am June22. For future reference what latitude and longitude are your times for? I'm in Toorak and I was wondering how I could calculate the solstice and other things for my location. I'm a curious sort.

Hi Mary, all our times and charts are for Melbourne at 37° 49’ 00 S and 144° 58’ 00 E. The times are local times adjusted for daylight savings. Now, as far as solstice and equinoxes go, they are all at the same Universal Time or GMT, and are given in local times.

Thanks - what I don't understand is how these solstice's (solsticii?) can be seen as marking the beginning of a season...? I would think they actually mark the mid-point of the season. E.g surely the summer solstice (when the sun reaches its zenith...) should really be mid summers day shouldn't it...?

Hi Alan, when seasons officially start and stop is a local convention that countries and communities adopt, and it depends on your latitude as well. If you are in the tropics then there are only two seasons: the wet and the dry. Our aboriginals have 3 to four seasons again depending on your latitude. See this great web site: http://www.bom.gov.au/iwk/climate_culture/Indig_seasons.shtml

The Summer Solstice in Melbourne is generally not the hottest time of the year as the earth hasn’t heated up fully, and is usually mid to end January. So you could say this is mid- summer in Melbourne. Season times as can be seen are purely local convention and are based about the solstice.

Lachlan
22 June, 2011 14:47

thanks alot, now I have lost a bet with richie saying that the winter solstice was yesterday. gosh

I think I just lost a bet with my daughter(12).
Great information and very easy to understand.
I also like that you answer people's questions and obviously know what you are talking about and that you are an Aussie site with relevant information to us Aussies.
Thank you

more need to said regarding the so called Australian - season starts. The simplilton accepted notion that the first day of a calender month like say Spring being Sept 1 or Summer as Dec 1 etc has as it's 'dubiuos' roots the need to push the period ahead of it's natural time is entrenched in institutions like retailers who want to announce the next sale ahead of competitors. Or moronic radio annoucers beating up something from nothing. Lets talk about that please so we can educate our people to the hijinx and robbery of a natural culture of which we as human being are more in tune with. Come on - get rid of it.

Hi Pauline, this link should give you the answers you are looking for.

Thomas & Matthew Kaufman (11 yo twins)
15 March, 2012 17:17

Thanks once again for your most informative expose on the equinoxes. Because of you I (Thomas) won a bet with my twin brother about the date of the autumnal equinox (southern hemisphere) - Matt thought it would be 21st March but I bet on the 20th march - so thanks for verifying my prediction and winning me some money.!!

I am an old man and once read that the British used March 1st as the Date that they put their servicemen here into Winter Uniforms and September 1st into Summer Uniforms. It is interesting to note that the Mother Country does not use the same dates. I agree with others that Australia should use the dates about three weeks later that most countries use.

Hi Don, the Planetarium staff have said that the dates on this link are correct. The Spring Equinox occurs at 00:49am on the 23rd Sept. 2012 but on the other side of the Earth it occurs on the 22nd September.

When seeing Earth diagram seasonal tilt models most people show Earth tilted toaward Left. Sometimes this is confusing because some use tilt to the Right and again makes one
confused on the 4-seasons like on Anartica vs. the Artic.

the first drawing is wrong. The seasons should be labeled in one hemisphere only. On the right part of the first drawing, the northern hemisphere receives more thermal energy from the sun. So the label should be summer in the northern hemisphere.

Hi wisegeek - we passed your comment by our Senior Curator of Astronomy, and the response was that the drawing you refer to is not wrong, it is correct and corresponds to the seasons in the southern hemisphere. The left most Earth is summer in the southern hemisphere and the right most Earth is winter in the southern hemisphere.

Dave
21 March, 2013 09:25

Hi. Is there an up dated page for "The Sun and the Seasons"? It only shows equinox and solstice dates to 2012. Like your site. Dave

Thank you so much, and greetings from Finland. This site is excellent, and helped me understand for the first time why North-facing sun is the hottest in Australia. We have it the other way round. Fascinating stuff!

It is amazing how ignorant the general population is when it comes to understanding the equinox as well as the solstice dates and why the earth has them! I have had many an argument that the earth goes away from the sun in winter and closer in summer. Don't get me started. Even Uni. students think this.

Hi Nat - All places on Earth experience the summer and winter solstice. The tilt of the Earth means that on the solstice days the rays of the sun strike either the latitudes defined by the Tropic of Cancer or The Tropic of Capricorn. On the northern hemisphere winter solstice there is no light above 66.5 degrees north (Polar Circle) but it is the summer solstice for the southern hemisphere where there is 24 hours of sunlight below 66.5 degrees south. If the earth did not tilt then there would be no solstice and no seasons (Swinburne University).

The Melbourne Museum has information sheets that help explain the path of the sun and the tilt of the Earth:

Been arguing with my boss about something. He is working in Cairns, North Queensland and he says that when working on the northern face of a building at this time of year he is in the sun all day but i think the sun would be coming from further to the south therefore putting him in the shade. Can you please let us know who is correct, than you.

Hi Luke, we chatted with the Planetarium staff for you, and they have found a great website that will settle the debate between you and your boss. According to http://aa.usno.navy.mil/data/docs/AltAz.php, for a short period around the longest day, 21st December, in Cairns, you would be in the shade, but for most of the year you would be in the Sun. Sorry Luke, I think your boss is right!

We're not sure what it is you're asking - could you please clarify your question?

Steve
13 January, 2014 09:10

Has the 'apparent' trajectory of the sun varied over time? I've been farming all my life meaning we are always outside and observing. I think the sun rise and set points, particularly more noticeable in the summer, have become much further south of east-west in recent 15 - 20 yrs. ie- is the earth tilting more or in a slight wobble? If so what sort of weather or physical affect is the earth enduring?

For any latitude the Sun’s rising and setting points on the horizon, and its daytime path across the sky, haven’t changed in their seasonal pattern in any meaningful way since humans began observing such things. Of course, the rising and setting positions and the Sun’s path all do shift graduallyduring the year but that regular seasonal/annual cycle is due to the steady tilt of Earth’s axis at 23.5 degrees. There is, however, a very small change to the tilt over tens of thousands of years. This is due to the gravitational influences of the Moon and other planets, and minor changes to the elliptical shape of Earth’s orbit around the Sun. That small (“wobble”) effect wouldn’t be noticeable in a human lifetime. A major earthquake can make a very tiny change to the tilt but that would not make a noticeable difference either to where the sun rises, sets, or its path in the sky.

Karl Bonner
14 January, 2014 17:11

Don't forget the cross-quarters on February 3/4, May 5/6, August 7/8 and November 6/7! They form the cusps of both the Chinese and Celtic/Druidic definition of the seasons.

Given the information in this explanation, which I agree with, can someone explain why Australia and New Zealand meteorologists and weather presenters use 1st day March, June, September and December to mark the 1st day of the seasons? I see the simplicity of using the calendar dates but it seems to deny the cosmic rhythm of the Universe that keeps us in-tune with nature.

Re woodys Question above, I too would like to know why Australia does this as it is the 2nd Sept today and everyone I speak to seems to be complaining it's still cold. I've explained the rationality of the earths orbit and the start of the actual seasons, but still I'm being stared at in dismay.

Hi Fiona - there are two main 'western' conventions on the commencement of the four seasons; those based on either the scientifc (Astronomical) basis determined by Equinoxes and Solstices, and those determined by the simple subdivision of the Gregorian Calendar. The nominated conventionin Australia, for better or worse, is calendar-based. There are many other interpretations of seasons (in most cases more than four) across numerous cultures, from Indigenous Australian, to Hindu, Tamil, Bengali and others.

marty burwood
11 October, 2014 06:49

It's erroneous to say that weather on earth is not determined by distance from the earth.There have been statements that the rotational axis of the earth has been shifted by large earthquakes, as well as the tilt. Also the fact that the Sun is, according to theoretical scientific prediction, halfway through its' life before it becomes a super nova.The sun as it burns internal fissionable material and ages, gradually gets brighter and of course hotter.The Sun has and is, the one main influence on Earth weather and climate.Human induced effects on our weather,climate,environment, with regard changes delivered through unsubstantiated and dubious 'scientific' evidence,therefor MUST BE negligible in comparison with Solar influences.I compare these fanatical protagonists with the opinionated and very superstitious 'flat earthers' of medieval times
(paradoxical because the answer was always in the 1st chapter of the Bible but you had to look for the clue). Another interesting event is what is called our cyclical equinox winds.A little more complex maybe because these winds can also be the result of anticyclone pressure(high) produced by Australian desert moving to our west and low pressure produced by the 'polar front' or our Antarctic moving into the Southern Ocean and up to 'southeasterly' NZ, produce these winds which incidentally rotate in an Anti-clockwise direction us being in the Southern Hemisphere.NW>SWetc etc.

Please - someone tell the announcers on the wireless and television's wasteland.
Start of Spring
Mid summer. Longest day 20-21-22 Dec
Mid winter. Shortest day. 20-21-22 June
Spring Equinox (middle of Spring) is September 20/21/22 (day 263/264/265)
365.25 / 8 = 45.66
365.25 / 4 = 91.31
Assuming each season is 1/4 of the year -
First day of spring is 45.66 days after mid winter
21 June is mid winter (+/- 1 day)
21 June is day 172 (non-leap year)
172 + 45.66 = 217.66
Day 218 is first day of spring
Day 218 is the 6th of August
et sequens
Day 309 the first day of Summer
Day 309 is the 5th of November
et cetera
ergo, the first day of summer this year falls on (or one day either side) Guy Fawkes' Day.
Just thinking out loud here.

I believe that the temple of the sphinx in Giza is oriented directly towards the rising sun at the summer solstice. Does this mean that it is oriented facing exactly due east geographically with the earth's north geographic pole (i.e. the earth's rotational axis) at 90 degrees to this direction?

Hi Ernemef, apologies for the delay in replying to your query. With Giza at latitude 29.9 degrees North, the Sphinx does face directly east at summer solstice. That is, at right angles to earth’s north-south geographical axis, or north geographical pole. For more info see:

Kikipanda; we're not sure if your question relates to the reversal of the equinixes and solstices between the northern and southern hemispheres, or if you are asking about the apparent timing differences of the event at different regions of the globe. Or, if you are curious about the slight timing differences from year to year.

In any case, each equinox and solstice event occurs only once and at one time (two of each per year), and depending on which side of the equator you are located determines what sort of equinox or solstice it is called, as seasons are reversed between hemispheres. For example, the Summer Solstice in Australia - the longest day - is the same event as the Winter Solstice in the UK - their shortest day. Astronomically its all the same event, but the position relative to the equator determines the season in which the event occurs, which therefore determines the name given to it.

The exact timing of solstices and equinoxes is a single occurence/event in each case - the timing is usually shown in UTC, which is functionally the same as Greenwich Mean Time. Often the timing are calculated to the relevant time zone for clarity as shown in the page above, where it is shown in in Australian Eastern Standard Time (AEST) of Australian Eastern Daylight Savings Time (AEDT) - these are the timings of these events as they occur in Melbourne.